On Wed, 27 Jul 2022 at 15:11, Masataka Ohta <mohta@necom830.hpcl.titech.ac.jp> wrote:
James Bensley wrote:
The BCM16K documentation suggests that it uses TCAM for exact matching (e.g.,for ACLs) in something called the "Database Array" (with 2M 40b entries?), and SRAM for LPM (e.g., IP lookups) in something called the "User Data Array" (with 16M 32b entries?).
Which documentation?
According to:
https://docs.broadcom.com/docs/16000-DS1-PUB
figure 1 and related explanations:
Database records 40b: 2048k/1024k. Table width configurable as 80/160/320/480/640 bits. User Data Array for associated data, width configurable as 32/64/128/256 bits.
means that header extracted by 88690 is analyzed by 16K finally resulting in 40b (a lot shorter than IPv6 addresses, still may be enough for IPv6 backbone to identify sites) information by "database" lookup, which is, obviously by CAM because 40b is painful for SRAM, converted to "32/64/128/256 bits data".
Hi Masataka, Yes I had read that data sheet. If you have 2M 40b entries in CAM, you could also have 1M 80 entries (or a mixture); the 40b CAM blocks can be chained together to store IPv4/IPv6/MPLS/whatever entries. Cheers, James.